1. Field of the Invention
The present invention relates to a method for transmitting data, an apparatus for recording data, a record (recording, recordable or recorded) medium, and an apparatus for reproducing data all of which are suitable to preventing illegal copying or incorrect use or applicable to a charging system.
2. Description of the Related Art
In recent days, with increase of capacity and prevail of a digital record medium like an optical disk, great significance has been placed on preventing illegal copying and inhibiting incorrect use of such a medium. Concretely, the digital audio data or the digital video data can be easily copied into a complete duplication with no degrade The computer data can be also more easily reproduced as the same data. In actual, hence, illegal copied data takes place in the market.
To prevent illegal copying of digital audio data or digital video data, the so-called SCMS (Serial Copy Management System) or CGMS (Copy Generation Management System) standards have been known. These standards are arranged so that a copy prohibitive flag is set to a specific portion of the recorded data. Even with these standards, hence, the data is allowed to be taken out by a method such as a dump copy.
As disclosed in Japanese Laid-open No. Showa 60-116030, another method has been proposed for encrypting a content of a computer data file and granting the encrypted content to registered users only. This method concerns with the system arranged to take the steps of distributing a digital record medium on which the encrypted data is recorded or making the encrypted digital data accessible to any user through a wired or wireless transmission path as a distributing format of data and providing the users having paid for the fee with key data for the necessary. Data so that these users may decode the encrypted digital data and use the data. It is thus desirable to establish the simple and useful encryption.